Luc Behr

Noncultured, Autologous, Skeletal Muscle Cells Can Successfully Engraft Into Ovine Myocardium

Background There is compelling evidence showing that cellular cardiomyoplasty can improve cardiac function. Considering the potential benefit of using noncultured muscle cells (little time, lower cost, reduced risk of contamination), we investigated the feasibility of grafting cells obtained directly after enzymatic dissociation of skeletal muscle biopsies into ovine myocardium. We hypothesized that those noncultured muscle cells would engraft massively. Methods and Results Autologous, intramyocardial skeletal muscle cell implantation was performed in 8 sheep. A skeletal muscle biopsy sample (≈10 g) was explanted from each animal. The sheep were left to recover for ≈3 hours and reanesthetized when the cells were ready for implantation. A left fifth intercostal thoracotomy was performed, and 10 epicardial injections of the muscle preparation (between 10 and 20 million cells) were carried out. All sheep were euthanized 3 weeks after myocardial implantation. Immunohistochemistry was performed with monoclonal antibodies to a fast skeletal isoform of myosin heavy chain. Skeletal myosin heavy‐chain expression was detected in all slides at 3 weeks after implantation in 8 of 8 animals, confirming engraftment of skeletal muscle cells. Massive areas of engraftment (from 2 to 9 mm in diameter) or discrete loci were noted within the myocardial wall. Conclusions Our results indicate that noncultured skeletal muscle cells can successfully and massively engraft in ovine myocardium. Thus, avoiding the cell culture expansion phase is feasible and could become a promising option for cellular cardiomyoplasty. (Circulation. 2003;107:3088‐3092.)

An ovine model of chronic heart failure: echocardiographic and tissue Doppler imaging characterization.

Abstract  Background and aim of the study: Heart failure in the western world is a major health‐care issue. In order to validate novel surgical or pharmacological treatments, reproducible animal models of left ventricular dysfunction are necessary. In the current study, we report our data and experience with a model of toxin‐induced heart failure in the sheep. Methods: Sequential intracoronary injections of doxorubicin (0.75 mg/kg) were carried out every 2 weeks until standard echocardiographic and tissue Doppler imaging detection of myocardial systolic dysfunction. The animals were assessed 1 month later and harvested. Indices of cardiac function from baseline to last day of protocol were recorded and their differences were evaluated by a Wilcoxon rank test for paired data. Results: Ten sheep received 2.5 ± 0.7 intracoronary injections of a cumulative dose of 88.8 ± 25 mg/m2 doxorubicin. All available parameters demonstrated signs of severe cardiac dysfunction with statistical significance. All hearts demonstrated severe histological lesions, some of which were consistent with doxorubicin‐induced toxicity. Conclusions: The present study shows that this ovine model is reproducible and stable. It can therefore be relevant to the study of chronic heart failure. It will be incorporated in our future studies concerning novel treatments (such as cell therapy) of nonischemic dilated cardiomyopathy.

Expandable Right Ventricular-to-Pulmonary Artery Conduit: An Animal Study

This study was performed to assess a new vascular stent graft as an expandable valved conduit for right ventricular outflow tract (RVOT) reconstruction in sheep. Conduits were constructed by sewing an 18-mm valved conduit inside a stent. Crimped to 16 mm, they were implanted either under or without extracorporeal circulation in seven (group A) and in five (group B) sheep, respectively. Six weeks and 3 mo after their insertion, conduits were dilated intraluminally. A valved stent was implanted percutaneously into conduits before they were killed. Two animals from group A recovered normally, whereas five animals had a complicated postoperative course. In group B, one died acutely due to kinking of the conduit. Balloon dilatations were performed in all surviving animals. First dilatations had a slight impact on valvular function in all animals but one, whereas second dilatations led to significant PR in all. Transcatheter valve implantation was performed successfully. When animals were killed, no bleeding was found around the surgically implanted device. In conclusion, we designed a biologic valved conduit for RVOT reconstruction that can be dilated sequentially to follow animal growth. This new device can have tremendous applications in children with congenital heart diseases involving the RVOT.

A new self-expandable transcatheter aortic valve for transapical implantation: feasibility in acute and chronic animal experiments.

Abstract Objectives. Transcatheter aortic valve implantation (TAVI) is currently expanding worldwide, however all available prostheses share some fundamental design drawbacks. We investigated the feasibility, safety and hemodynamic performance of the innovative transapical Acurate TA™ self-expandable device, which has the unique advantage of offering anatomically correct self-alignment within the aortic root. Design. Transapical TAVI was performed in six acute swine and six chronic sheep procedures, with follow-up of 7, 14, 21, 28, 60 and 90 days. TAVI was performed under TEE and angiographic guidance without rapid pacing. Results. A partial sternotomy approach was used to access the LV-apex. All valve implantations were performed as planned and all animals survived the implantation procedure. After deployment, no migration, embolization or coronary obstruction was observed during the observation period. Intraoperative TEE examination identified no signs of intravalvular leakage or valve dysfunction. Transvalvular mean pressure gradients were 5.4 ± 2.2 mmHg decreasing during follow-up (1.6 ± 0.8 mmHg, 1.8 ± 0.8 mmHg, 1.3 ± 0.2, 1.8 ± 0.7 mmHg, 1.6 ± 0.8 mmHg), with a slight increase atday 90 (4.0 ± 2.4 mmHg, P < 0.05). Macroscopic examination at necropsy showed correct anatomical positioning of the valve stent without any signs of structural valve deterioration. Conclusions. These first results of the innovative self-expandable transapical ACURATE TA™ device explore the feasibility and safety of anatomically correct off-pump implantation with optimal hemodynamic results.

Echoguided closed commissurotomy for mitral valve stenosis in a dog

Surgical treatment of mitral stenosis (MS) usually consists of open mitral commissurotomy (MC) or percutaneous balloon MC, which require a cardiopulmonary bypass or transseptal approach, respectively. We describe here the first surgical management of congenital MS in a dog using a less invasive procedure, a surgical closed MC under direct echo guidance. A 5-year-old female Cairn terrier was referred for ascites, weakness, and marked exercise intolerance for 2 months, which was refractory to medical treatment. Diagnosis of severe MS associated with atrial fibrillation (AF) was confirmed by echo-Doppler examination and electrocardiography. Poor response to medical treatment suggested a corrective procedure on the valve was indicated. However, due to the cost and high mortality rate associated with cardiopulmonary bypass, a hybrid MC was recommended. A standard left intercostal thoracotomy was performed and three balloon valvuloplasty catheters of differing diameters were sequentially inserted through the left atrium under direct echo guidance. Transesophageal echocardiography revealed a 62% reduction in the pressure half-time compared to the pre-procedure. Thirteen months after surgery the dog is still doing well with resolution of ascites and a marked improvement of most echo-Doppler variables.

Toward the development of a fully elastic mitral ring: Preliminary, acute, in vivo evaluation of physiomechanical behavior

OBJECTIVES The optimal repair of functional mitral regurgitation is still debated. No device is able to simultaneously abolish mitral regurgitation and replicate natural mitral annular dynamics. We have tested a fully elastic mitral ring in an acute animal study with the purpose of evaluating (1) ring design and implantation technique, (2) elastic performance, and (3) acute effects on the native mitral annulus. METHODS Ten healthy sheep underwent surgical implantation of mitral devices, the elastic component of which is represented by a helicoid metallic spring. Preimplantation and postimplantation echocardiographic parameter measurements to evaluate annular dynamics and ventricular function comprise mitral annular motion, systolic tissue Doppler imaging peak wave, transmitral pressure gradient, peak transmitral flow velocity, and ejection fraction. Postimplantation angiographic analysis allowed measurement of the mitral annular area and perimeter variations by means of segmentation of the radiopaque mitral device contour. RESULTS No significant difference in terms of ejection fraction (P = .13) and systolic tissue Doppler imaging peak wave (P = .87) was found before and after implantation. Mitral annular motion (1.16 cm) was preserved. The percentage of systolic annular reduction derived from angiographic analysis was 14.1% (range, 7.7%-19.7%) in terms of area and 7.2% (range, 4.9%-10.0%) in terms of perimeter. CONCLUSIONS A mitral elastic ring, implantable by using a standard technique, acutely preserves mitral annular dynamics, allowing area and perimeter changes. Further chronic study is needed to verify the biocompatibility and durability of the device.

Successful Treatment of a Congenital Pulmonic Valvular Stenosis in a Snow Leopard (Uncia uncia) by Percutaneous Balloon Valvuloplasty

Abstract A 3-yr-old intact female snow leopard (Uncia uncia) was evaluated for progressive apathy, lethargy, and decreased appetite. Cardiac auscultation revealed a left basal grade IV/VI systolic ejection murmur, and an echocardiogram confirmed a severe pulmonic valvular stenosis (pressure gradient of 98 mm Hg). The lesion was managed by balloon valvuloplasty, resulting in a marked pressure gradient reduction (30 mm Hg). The cat recovered well, and clinical signs resolved. This is the first description of a pulmonary valve stenosis and management with balloon valvuloplasty in a wild felid.

Surgical Treatment of Cor Triatriatum Sinister in a Cat Under Cardiopulmonary Bypass.

OBJECTIVE To report the surgical repair of cor triatriatum sinister (CTS) incorporating heart-beating cardiopulmonary bypass (CPB) in a cat. STUDY DESIGN Clinical case report. ANIMAL Fourteen-month-old, 5.9-kg male castrated Maine Coon cat. MATERIALS AND METHODS The cat had a 3 month history of inappetance, weight loss, and recurrent pulmonary edema. CTS with severe systolic pulmonary arterial (SPA) hypertension (124 mm Hg) was diagnosed by 2D echocardiography, color flow and continuous wave Doppler modes, and left atrial and pulmonary angiography. Surgery was performed through a left intercostal thoracotomy. CPB was initiated and the heart was kept beating. The left atrial appendage was opened and the intra-atrial membrane was excised. RESULTS After 48 hours, the cat was doing well. Reduced SPA pressure (52 mm Hg) with decreased right heart enlargement was observed on ultrasound examination and the cat was discharged 6 days after surgery with oral antibiotics for 10 days, aspirin, and furosemide. Four months after surgery, the cat presented with increased activity and weight gain and was completely asymptomatic. Transthoracic echocardiography showed a marked improvement of all echo-Doppler variables with disappearance of SPA hypertension (24 mm Hg). Four years after surgery, the cat was still doing well with no recurrence of clinical signs despite the lack of medical treatment. CONCLUSION CTS in the cat may be successfully treated by surgery facilitated by use of CPB leading to early and long-term substantial improvement in clinical status and cardiac function. CTS can safely be repaired under CPB in cats.

Intracardiac echocardiography: use during transcatheter device closure of a patent ductus arteriosus in a dog ☆

Intracardiac echocardiography (ICE) is used in humans for percutaneous interventional procedures, such as transcatheter device closures. Intracardiac echocardiography provides high-resolution imaging of cardiac structures with two-dimensional, M-mode, Doppler, and also three-dimensional modalities. The present report describes application of ICE during transcatheter occlusion of patent ductus arteriosus using a canine ductal occluder in a dog for which transesophageal echocardiography could not provide an optimal acoustic window.

Compensatory renal growth after unilateral or subtotal nephrectomy in the ovine fetus

Background:Clinical and experimental studies show that unilateral (1/2Nx) and subtotal nephrectomy (5/6Nx) in adults result in compensatory renal growth without formation of new nephrons. During nephrogenesis, the response to renal mass reduction has not been fully investigated.Methods:Ovine fetuses underwent 1/2Nx, 5/6Nx, or sham surgery (sham) at 70 d of gestation (term: 150 d), when nephrogenesis is active. At 134 d, renal function was determined, fetuses were killed, and kidneys were further analyzed at the cellular and molecular levels. Additional fetuses subjected to 5/6Nx were killed at 80 and 90 d of gestation to investigate the kinetics of the renal compensatory process.Results:At 134 d, in 1/2Nx, a significant increase in kidney weight and estimated glomerular number was observed. In 5/6Nx, the early and marked catch-up in kidney weight and estimated glomerular number was associated with a striking butterfly-like remodeling of the kidney that developed within the first 10 d following nephrectomy. In all groups, in utero glomerular filtration rates were similar.Conclusion:Compensatory renal growth was observed after parenchymal reduction in both models; however, the resulting compensatory growth was strikingly different. After 5/6Nx, the remnant kidney displayed a butterfly-like remodeling, and glomerular number was restored.